Connecting a plurality of tissue parts

ABSTRACT

A device for fixing a first and a second tissue part or a tissue part and an implant part to each other is provided, providing a fastener including a thermoplastic material and a fastening instrument. The fastening instrument includes a first instrument component with a first contact surface facing toward a distal side and a second instrument component has a foot with a second contact surface distally of the first contact surface and facing toward a proximal side. The first instrument component and the second instrument component are displaceable with respect to each other, so that the fastener is compressible between the first and second contact surfaces by application of a relative force between the components. The instrument also includes an energy source for coupling mechanical energy into one of the instrument components to soften and/or melt an end portion of the fastener.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention is in the field of medical technology and relates tomethods and devices of fixing two or more tissue parts to each other orfor affixing at least one tissue part to an implanted device.

Description of Related Art

In surgery, it is often necessary to affix two tissue parts to eachother or to affix an implanted device—such as a so-called mesh—to atissue part. While a lot of methods for affixing two bone parts to eachother have become known, these rely on the anchoring capacity of thehard tissue in which fasteners may be anchored safely of being removedby pulling forces. It is, however, often a challenge to affix two tissueparts to each other which are not bone tissue but for example cartilageor soft tissue. The same challenge exists if an implanted device is tobe affixed to cartilage or soft tissue.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide methods and devicesfor fixing tissue parts (portions or organs of human or animal tissue)to each other or of fixing an implant part to a tissue part, the methodsand devices overcoming drawbacks of prior art methods and devices and/orbeing especially suitable for tissue parts that are not bone tissueand/or not dimensionally stiff.

In accordance with an aspect of the invention, a method of fixing afirst and a second tissue part or a tissue part and an implant part toeach other is provided. The method comprises the steps of providing afastener comprising a thermoplastic material (generally at least at anend portion), providing a fastening instrument, the fastening instrumentcomprising a first instrument component with a first contact surface anda second instrument component with a second contact surface, the firstinstrument component and the second instrument component beingdisplaceable with respect to each other, positioning the fastener andthe fastening instrument so that the fastener reaches through a commonopening of the first and second tissue or implant parts, which commonopening is constituted by a first through opening of the first tissue orimplant part and a second through opening of the second tissue orimplant part, the first and second through openings aligned with eachother, and so that the first contact surface is in contact with aproximal end face of the fastener and the second contact surface is incontact with a distal end face of the fastener. The method alsocomprises the steps of submitting the first and second instrumentcomponents to a relative force so that the fastener is pressed betweenthe first and second contact surfaces, and simultaneously couplingmechanical vibrations into at least one of the first and secondinstrument components with a vibration power and during a vibration timesufficient to at least partially soften and/or melt an end portion underthe common impact of the relative force and the vibrations, and usingthe softening and/or melting of the end portion to provide the endportion with a head with a diameter greater than a diameter of at leastone of the through openings, and letting the softened and/or melteddistal end portion re-solidify.

The invention also pertains to thermoplastic material (for example anyone of the hereinafter explicitly mentioned materials) for use as afastener or fastener part(portion) in such a methods. Especially, suchuse pertains to a fastener part that can be deformed and/or melted to beprovided with a distal or proximal head, either by deformation of thethermoplastic material or by the thermoplastic material being welded toan also thermoplastic head shaping element as explained hereinafter. Allremarks and teachings in this text that relate to the method alsopertain to the thermoplastic material for use as a fastener or fastenerpart in such a method.

Returning to the method, the steps of positioning the fastener and ofpositioning the instrument may be done, depending on the set-up andpossibly on the wishes of the surgeon, in any sequence or simultaneouslyor partially simultaneously.

In the step of using the softening and/or melting of the end portion toprovide the end portion with a head, the end portion may be caused todeform, under the common impact of the relative force and thevibrations, to yield the head.

This may for example be done such that the end portion itself isdeformed into the head, i.e. the head material may be deformed endportion material.

In an alternative embodiment, the instrument component at the contactsurface of which the head portion is formed may comprise a head formingelement that under the impact of the vibrations and the relative forceis welded to the fastener's end portion so that the fastener after thestep of letting the end portion re-solidify comprises the initialfastener material plus the head forming element material. To this end,the named instrument component (for example the second instrumentcomponent, which is in contact with the distal end of the fastener andwhich has a foot) may comprise a head forming element dispenser.

The through openings in the tissue parts or the tissue part and theimplant part may be naturally present (or pre-manufactured in case of animplant part), may be pre-made in a preparation step (for example bydrilling) prior to the insertion of the fastener, or may be made by theinsertion of the fastener that then for example comprises a piercing tipor edge (or generally a reaming capacity). Combinations are possible,for example a pre-made through opening in one part combined with anopening made by the insertion in the other part, or any othercombination. Also it is possible that the opening is partly pre-made;for example a pre-made or naturally present opening with a first,smaller cross-sectional area exists and is additionally widened by theinsertion of the fastener to a second, larger cross sectional area bythe insertion of the fastener.

In embodiments, the fastener is generally inserted from a proximal side,which side is also the side that can be accessed by the surgeon duringoperation. Then, the end portion that is deformed to yield a head is thedistal end portion.

In alternative embodiments, the fastener is inserted from a distal side.To this end, the fastener may be, prior to the placing of the instrument(or at least of the second instrument component of the instruments areseparate) at the operation site, provisionally attached to the secondinstrument component. As a possibility, the second instrument componentmay comprise a dispenser that is, during the process, in contact withthe distal end of the fastener and sequentially dispenses a plurality offasteners.

As soon as the softening and/or melting sets in, the relative force willcause a relative movement of the first and second instrument components,whereby the first and second contact surfaces are moved towards eachother and the fastener is thus compressed.

In an aspect of the invention, it is therefore proposed to usemechanical vibrations, such as ultrasonic vibrations, to deform an endportion, (that may be a distal portion or a proximal portion) of afastener into a (distal or proximal, respectively) head. As aconsequence, the fastener functions as a kind of rivet. In this, thefastener initially may be a fastening pin of arbitrary cross section.Also, the fastener may optionally comprise a pre-formed head on theother (proximal or distal, respectively) side

In many embodiments, the second instrument component has a proximalshaft portion and a distal foot portion, wherein the second contactsurface is formed as a proximally facing surface of the foot portion ora part thereof. In embodiments, the second contact surface may beapproximately perpendicular to a proximodistal fastener axis.

In many embodiments, the first instrument component—that impinges on thefastener from the proximal side thereof—is used to cause the mechanicalvibrations to impinge on the fastener, for example by coupling themechanical vibrations into the fastener. To this end, the instrument mayfurther comprise a mechanical vibration generator, such as a vibrationgenerator that comprises a piezoelectric element and an electricexcitation circuitry for the piezoelectric element. The first instrumentcomponent may act as a sonotrode of the instrument, which sonotrode iscoupled to the vibration generator. The instrument may further comprisean instrument housing, in which the vibration generator with thesonotrode coupled thereto is housed. The housing may but need notcompletely seal off the vibration generator. The second instrumentcomponent then may be a counter element that is for example movablymounted relative to the first instrument component (and to the housingif present) or that can be held by the surgeon like a separate tool. Thesecond instrument component may comprise a distal counter portion (thatmay be the foot portion) with the second contact surface facing towardsthe proximal side and a shaft portion extending proximally from thecounter portion. The shaft portion may be slidingly (or pivotingly)mounted to the housing and the relative force may be applied at theshaft portion.

As an option, in embodiments of the invention, the second instrumentcomponent may be configured to deflect the mechanical oscillationsgenerated by the vibration generator. This may for example be done by aninstrument component that has a vibrating element into which transversaloscillations along an input axis are deflected into transversaloscillations along an output axis. An example of such a device is taughtin WO 2007/101 362. Embodiments that comprise the deflection ofmechanical oscillations are especially suited in situations where astraight access along the axis of the fastener is difficult and wherethe operation site is better accessed from sideways. It is one of theadvantages of embodiments of the invention that they are also suited forinsertion by an access from sideways.

Also as an option, a plurality of fasteners can be used. For example,the plurality of fasteners can be distributed over the tissue/implantparts. The heads of neighbouring fasteners can then optionally beconfigured to be in contact with each other or be welded to each other.

In accordance with an option, the tissue parts fixed to each other areat the same time provided with one or more flexible planar structure(s)of an artificial material for reinforcement. As an example, suchflexible planar structure may be a mesh. Such flexible planar structuremay be provided on an outer side of the tissue portions, on outer sidesof tissue portions and/or between the tissue portions. Alternatively, ifan implant part is fixed to a tissue part, such a flexible planarstructure may constitute the implant part.

The first and second tissue parts may be parts of a common tissueelement or organ. For example, the first and second tissue parts may beportions of a ruptured or partially ruptured tissue element or organ ofwhich a rupture has to be healed. The first and second tissue parts asan alternative may be separate elements and/or organs, for example aflat, bendable implant to be affixed to a flat, bendable tissue part.

The first and second tissue parts may for example by layers or otherparts of cartilage. An application of aspects of the method of theinvention is a repair of the meniscus. In the preparation for themethod, end portions of a ruptured meniscus are bent to be laid on topof each other, and the first and second openings are made into theassembly of the portions on top of each other.

As an alternative to cartilage, at least one of the first and secondtissue parts may be parts of other tissue, especially soft tissue, or atissue replacement material. One of the first and second tissue partsmay also be an implant to be affixed to a tissue part. In this text, forreasons of simplicity the parts to be affixed to each other are oftenreferred to as “first and second tissue parts”, however, embodiments ofthe invention also pertain to in-situ affixing an artificial element(implant) to a tissue part.

The invention also applies to fixing more than two tissue parts, forexample three or more tissue parts to each other in one step, by layingthe three (or more) tissue parts on top of each other and introducingthe fastener in a common, aligned hole.

While many embodiments of methods and devices according to the inventionare especially suited for affixing cartilage or soft tissue parts toeach other or of affixing artificial devices (implant parts) to suchtissue, the application to dimensionally stiff bone tissue is notexcluded in all embodiments. Rather, the methods and devices may also besuitable for bone tissue, especially for flat bone (ossa plana) or weakbone tissue.

It is a further option to use the method and device to fasten afilament-like element, such as a thread surgical (especially a threadfor a surgical suture), to tissue. As an example, such a filament-likeelement may be attached to the tissue parts or the tissue part and theimplant part fixed to each other during the fixation process. Forexample a loop of the filament-like element may be wound around a shaftof the fastener and held by a head of the fastener (a pre-fabricatedhead or the head that is provided using the softening and/or melting ofthe end portion). As another example, such a filament-like elementconstitutes the implant part, the loop then forming the through openingaligned with a through opening in the tissue part.

More in general, the invention according to an aspect concerns a methodof anchoring a filament-like element, especially a thread, in a tissuepart. The method comprises the steps of providing a fastener, thefastener comprising a first head at a first fastener end portion;providing a fastening instrument, the fastening instrument comprising afirst instrument component with a first contact surface and a secondinstrument component with a second contact surface, the first instrumentcomponent and the second instrument component being displaceable withrespect to each other; and positioning the fastener and the fasteninginstrument so that the fastener reaches through an opening of thetissue, and so that the first contact surface is in contact with aproximal end face of the fastener and the second contact surface is incontact with a distal end face of the fastener. The method alsocomprises the steps of coupling, by at least one of the instrumentcomponents, energy into the fastener to cause a second fastener endportion to at least partly soften and/or melt, and to use the softeningand/or melting of the second end portion to provide the second endportion with a second head with a diameter greater than a diameter theopening; and letting the softened and/or melted end portion re-solidify,wherein filament-like element forms a loop around the fastener, adiameter of the loop being smaller than at least one of the first headand the second head.

In accordance with an embodiment, the filament-like element ispositioned by a positioning element (such as a needle or other element,possibly the fastener itself) to which it is mounted. This element inaccordance with an embodiment is inserted through the tissue part from adistal side in a manner that an end portion of the filament-likeelement, which end portion forms the loop, is accessible from theproximal side.

If the positioning element is a needle, it may be a needle of a shapememory material and be guided in a channel of the second instrumentcomponent to be pushed from the proximal side, to pierce the tissue fromthe distal side and to take along the thread (or other filament-likeelement) through the tissue back to the proximal side.

In many embodiments, the second instrument component (or the firstinstrument component if the fastener is introduced from the distal side)has a head shaping portion that forms the second (or first,respectively) contact surface. The head shaping portion may be providedas a for example shallow indentation—if present in the counterportion/foot portion—a bottom of which forms the second (first) contactsurface. The head shaping portion may further comprise at least oneenergy director or a partitioning structure ensuring a desired materialflow to different directions. The head shaping portion may for examplehave a concave or partially concave shape. By the method according to anaspect of the invention, the distal head that is shaped comprisessurface portions that are a replica of the head shaping portion.

In any aspect of the method, one or an arbitrary (meaningful)combination of the following may occur. Mechanical oscillations may becoupled into the fastener from the first instrument component during thestep of positioning the fastener. The fastener may be generallypin-shaped with a cylindrical portion (of any suitable cross section,i.e. circular or non-circular), possibly with a pre-formed (proximal, ordistal) head portion. As an alternative to being pin-shaped, thefastener may comprise a plurality of shafts that are connected by aproximal (or distal) bridge portion, the shafts being configured to bereach through a corresponding number of common openings of the first andsecond tissue or implant parts. The fastener may comprise a pre-madeproximal (or distal) head portion that forms a shoulder that abutsagainst the first tissue part when the force and the vibrations arecoupled into the fastener. The fastener may consist of thermoplasticmaterial, or the fastener may comprise a thermoplastic component (thatcomprises at least the—distal or proximal—end portion) and a componentthat is not thermoplastic.

During the simultaneous steps of coupling vibrations into the fastenerand compressing the fastener between the first and second instrumentcomponents, a thermoplastic portion at the other end (the proximal endof the fastener is inserted from the proximal side or the distal end ifthe fastener is inserted from the distal side) of the (for examplepin-shaped) fastener may be deformed into a proximal/distal furtherhead. If the fastener comprises a pre-shaped further (proximal/distal)head that is made of a thermoplastic material, the pre-shaped furtherhead portion may optionally be shaped further, so that for example itsdistal/proximal shoulder has a shape adapted to the shape of the firsttissue part.

The fastener may comprise a proximal guiding and/or retaining structureinto which a corresponding guiding and/or retaining element of the firstinstrument component may engage so as to guide and/or hold the fastenerduring insertion thereof.

In addition to the vibration generator, the instrument may furthercomprise a force applicator for automatedly applying the relative force.Such a force applicator may for example comprise a spring that may bepre-tensioned prior to the process, and the spring force may be releasedsimultaneously with generating the vibrations. Alternatively, a forceapplicator may comprise another driving mechanism such as anelectrically actuated mechanism.

In addition to a force applicator or as an alternative thereto, theinstrument may comprise a handle to allow the surgeon to apply the forcehimself. Then, the instrument may optionally further comprise aresistance spring against the force of which the relative force has tobe applied and the first and second instrument components have to bemoved relative to one another. Such a spring may ease the releasing ofthe instrument components from the fastener after solidification of thethermoplastic material.

Thermoplastic material of the fastener may be caused to adhere to thetissue of the first and/or the second tissue part and/or be caused tointerpenetrate structures of the first and/or second tissue part tocreate a positive-fit connection. This may be thermoplastic material ofthe proximal and/or distal head portion and/or of a remainingcylindrical portion between the head portions.

A fastening instrument for fixing a first and a second tissue part or atissue part and an implant part to each other or for anchoring afilament-like element, for example a thread, in a tissue. The fasteninginstrument comprises a first instrument component with a first contactsurface and a second instrument component with a second contact surface,the first instrument component and the second instrument component beingdisplaceable with respect to each other, wherein the first instrumentcomponent has a first contact surface facing towards a distal side. Thesecond instrument component has a foot with a second contact facedistally of the first contact face and facing towards a proximal side,so that a fastener is compressible between the first and second contactfaces by application of a relative force between the first and secondinstrument components. The instrument further comprising an energysource for coupling mechanical energy into at least one of the first andsecond instrument components.

The contact face, in contact with which the end portion is provided witha head, may comprise a head shaping portion. For example for a fastenerinserted from a proximal side, the second contact face of the foot ofthe second instrument component then is formed as a head shapingportion. If the fastener is inserted from the distal side, the distalend face of the first instrument component may comprise a head shapingportion. In addition, the in each case other contact face may optionallyalso comprise a head shaping portion.

At least the first and second instrument components are capable of beingsterilized.

A kit of parts a for fixing a first and a second tissue part or a tissuepart and an implant part to each other comprises an instrument of theabove-described kind and further comprises at least one fastener, thefastener comprising a proximal and a distal end, wherein the proximaland/or the distal end comprises thermoplastic material that can be madedeformable/flowable by the impact of the mechanical energy. The fastenermay be generally pin-shaped with an optional proximal head and with anoptional distal cutting and/or punching and/or reaming structure.

For example, the at least one fastener is provided in a sterile package.

As an alternative to mechanical vibrations, other forms of mechanicalenergy may be used to make the thermoplastic materialflowable/deformable. This especially includes rotational movement of thefastener relative to the counter element. As yet another alternative,electromagnetic radiation may be used to make the thermoplastic materialflowable/deformable. To this end, the fastener may be essentiallytransparent with a radiation absorber especially in the distal region.The radiation may be coupled into the fastener by means of a laser orother radiation source.

In this text the expression “thermoplastic material being capable ofsoftening and/or being melted by the impact of mechanical vibration” orin short “liquefiable thermoplastic material” or “liquefiable material”is used for describing a material comprising at least one thermoplasticcomponent, which material becomes liquid or flowable when heated, inparticular when heated through friction i.e. when arranged at one of apair of surfaces (contact faces) being in contact with each other andvibrationally or rotationally moved relative to each other, wherein thefrequency of the vibration is between 2 kHz and 200 kHz, preferably 20to 40 kHz and the amplitude between 1 μm and 100 μm, preferably around10 to 30 μm. Such vibrations are e.g. produced by ultrasonic devices ase.g. known for dental applications. For being able to be load-bearingconnection, the material may have elasticity coefficient of more than0.5 GPa, preferably more than 1 GPa. The elasticity coefficient of atleast 0.5 GPa also ensures that the liquefiable material is capable oftransmitting the ultrasonic oscillation with such little damping thatinner liquefaction and thus destabilization of the liquefiable elementdoes not occur, i.e. liquefaction occurs only where the liquefiablematerial is at the liquefaction interface to the stop face. Theplastification temperature is preferably of up to 200° C., between 200°C. and 300° C. or even more than 300° C. Depending on the application,the liquefiable thermoplastic material may or may not be resorbable.

Suitable resorbable polymers are e.g. based on lactic acid and/orglycolic acid (PLA, PLLA, PGA, PLGA etc.) or polyhydroxyalkanoates(PHA), polycaprolactones (PCL), polysaccharides, polydioxanones (PD),polyanhydrides, polypeptides or corresponding copolymers or blendedpolymers or composite materials containing the mentioned polymers ascomponents are suitable as resorbable liquefiable materials.Thermoplastics such as for example polyolefins, polyacrylates,polymetacrylates, polycarbonates, polyamides, polyesters, polyurethanes,polysulphones, polyaryl ketones, polyimides, polyphenyl sulphides orliquid crystal polymers (LOPS), polyacetals, halogenated polymers, inparticular halogenated polyoelefins, polyphenylene sulphides,polysulphones, polyethers, polypropylene (PP), or correspondingcopolymers or blended polymers or composite materials containing thementioned polymers as components are suitable as non-resorbablepolymers. Examples of suited thermoplastic material include any one ofthe polylactide products LR708 (amorphous Poly-L-DL lactide 70/30), L209or L210S by Böhringer Ingelheim.

Specific embodiments of degradable materials are Polylactides like LR706PLDLLA 70/30, R208 PLDLA 50/50, L210S, and PLLA 100% L, all ofBöhringer. A list of suitable degradable polymer materials can also befound in: Erich Wintermantel und Suk-Woo Haa, “Medizinaltechnik mitbiokompatiblen Materialien und Verfahren”, 3. Auflage, Springer, Berlin2002 (in the following referred to as “Wintermantel”), page 200; forinformation on PGA and PLA see pages 202 ff., on PCL see page 207, onPHB/PHV copolymers page 206; on polydioxanone PDS page 209. Discussionof a further bioresorbable material can for example be found in C ABailey et al., J Hand Surg [Br] 2006 April; 31(2):208-12.

Specific embodiments of non-degradable materials are: Polyetherketone(PEEK Optima, Grades 450 and 150, Invibio Ltd), Polyetherimide,Polyamide 12, Polyamide 11, Polyamide 6, Polyamide 66, Polycarbonate,Polymethylmethacrylate, Polyoxymethylene, or polycarbonateurethane (inparticular Bionate by DSM). An overview table of polymers andapplications is listed in Wintermantel, page 150; specific examples canbe found in Wintermantel page 161 ff. (PE, Hostalen Gur 812, Höchst AG),pages 164 ff. (PET) 169ff. (PA, namely PA 6 and PA 66), 171 (PTFE), 173ff. (PMMA), 180 (PUR, see table), 186 ff. (PEEK), 189 ff. (PSU), 191(POM—Polyacetal, tradenames Delrin, Tenac, has also been used inendoprostheses by Protec).

The liquefiable material having thermoplastic properties may containforeign phases or compounds serving further functions. In particular,the thermoplastic material may be strengthened by admixed fillers, forexample particulate fillers that may have a therapeutic or other desiredeffect. The thermoplastic material may also contain components whichexpand or dissolve (create pores) in situ (e.g. polyesters,polysaccharides, hydrogels, sodium phosphates) or compounds to bereleased in situ and having a therapeutic effect, e.g. promotion ofhealing and regeneration (e.g. growth factors, antibiotics, inflammationinhibitors or buffers such as sodium phosphate or calcium carbonateagainst adverse effects of acidic decomposition). If the thermoplasticmaterial is resorbable, release of such compounds is delayed.

If the liquefiable material is to be liquefied not with the aid ofvibrational energy but with the aid of electromagnetic radiation, it maylocally contain compounds (particulate or molecular) which are capableof absorbing such radiation of a specific frequency range (in particularof the visible or infrared frequency range), e.g. calcium phosphates,calcium carbonates, sodium phosphates, titanium oxide, mica, saturatedfatty acids, polysaccharides, glucose or mixtures thereof.

Fillers used may include degradable, osseostimulative fillers to be usedin degradable polymers, including: β-Tricalciumphosphate (TCP),Hydroxyapatite (HA, <90% crystallinity; or mixtures of TCP, HA, DHCP,Bioglasses (see Wintermantel). Osseo-integration stimulating fillersthat are only partially or hardly degradable, for non degradablepolymers include: Bioglasses, Hydroxyapatite (>90% cristallinity),HAPEX®, see S M Rea et al., J Mater Sci Mater Med. 2004 September;15(9):997-1005; for hydroxyapatite see also L. Fang et al., Biomaterials2006 July; 27(20):3701-7, M. Huang et al., J Mater Sci Mater Med 2003July; 14(7):655-60, and W. Bonfield and E. Tanner, Materials World 1997January; 5 no. 1:18-20. Embodiments of bioactive fillers and theirdiscussion can for example be found in X. Huang and X. Miao, J BiomaterApp. 2007 April; 21(4):351-74), J A Juhasz et al. Biomaterials, 2004March; 25(6):949-55. Particulate filler types include: coarse type: 5-20μm (contents, preferentially 10-25% by volume), sub-micron (nanofillersas from precipitation, preferentially plate like aspect ratio>10, 10-50nm, contents 0.5 to 5% by volume).

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter, embodiments of the invention are described referring todrawings. In the drawings which are schematics and not to scale, samereference numerals refer to same or corresponding elements. The figuresshow:

FIG. 1 is an elevation view of an instrument with a fastener positionedto affix two tissue parts to each other;

FIG. 2 is an elevation view showing the fastener and the instrumentduring the process of affixing the two tissue parts to each other;

FIGS. 3a and 3b are elevation views showing an alternativefastener-instrument-arrangement prior in two different process steps ofa process of affixing two tissue parts to each other;

FIG. 4a-4c are elevation views showing yet another embodiment of afastener-instrument arrangement during different process steps ofaffixing two tissue parts to each other;

FIG. 5a is a sectional elevation view of a material guiding and energydirecting structure;

FIG. 5b is a plan view of a possible shape of a head shaping portion;

FIG. 6 is an elevation view of a further embodiment of an instrument;

FIG. 7 is a perspective view that illustrates an arrangement thatcomprises in-plane reinforcement of the tissue parts;

FIGS. 8a and 8b are elevation views showing a way of anchoring a wire orthread;

FIG. 9 is an elevation view of a magazine for sequentially dispensing aplurality of fasteners;

FIG. 10 is a perspective view of a fastener;

FIG. 11 is a perspective view of a fastener;

FIG. 12 is a perspective view of a foot;

FIG. 13 is a perspective view of a foot;

FIG. 14 is a perspective view of a fastener head forming element; and

FIG. 15 is a perspective view of a fastener head forming element.

DETAILED DESCRIPTION OF THE INVENTION

The first tissue part 1 and the second tissue part 2 shown in FIG. 1 mayfor example be parts of a ruptured meniscus. Edge portions of themeniscus along the rupture are positioned on top of each other.Alternatively, the first tissue part and the second tissue part may beother tissue portions to be affixed to each other; one of them may alsobe a tissue replacement and/or reinforcement implant. For example one orboth of the tissue parts may be other cartilaginous tissue or a ligamentor tendon or a intervertebral disc, or skin etc. A tissue replacement orreinforcement implant may for example be a mesh or allograft orartificial ligament or tendon or replacement of a cartilaginous tissue,etc. The method is not restricted to a particular kind of tissue/orimplant but is especially suited for tissue that is different from boneor bone replacement material.

The instrument 3 comprises an instrument housing 4 in which anultrasonic transducer (not shown) or other vibration generating deviceis arranged. The ultrasonic transducer or other vibration generatingdevice is operable to set a sonotrode 6, being the first instrumentcomponent, into vibration. The second instrument component 11 is acounter element with a counter element shaft 12 and a foot 13. The shaft12 is slidingly mounted to the housing 4 or (or to an other elementcoupled to the first instrument component). In the depictedconfiguration, this is done by a guiding element 8 affixed to thehousing 4, the guiding element with a through hole having an innerdiameter adapted to an outer diameter of the shaft portion and servingas guide an defining a relative, proximodistal movement direction.

The fastener 21 in the depicted configuration is pin-shaped with acylindrical body or shaft 23 (that may be circular in cross section orhave an other cross section adapted to the desired geometry) with anoptional pre-formed proximal head 22 and consists of a thermoplasticmaterial. A proximal guiding hole 25 is adapted to a holding protrusionof the sonotrode 6, so that the fastener 21 can be attached to thesonotrode. The fastener has a slightly tip-shaped distal en portion 24.

In the depicted configuration, a common opening 31 of the first andsecond tissue parts is pre-made; the diameter is, however, smaller thanthe diameter of the fastener. When the fastener is introduced into theopening, ultrasonic vibrations may be coupled into it so as to assistthe widening process of the opening 31.

The foot 13 of the counter element 11 has an indentation 14 that isaligned to the sonotrode 6 and, if mounted, to the fastener. Thefastener axis 41 may for example be an axis of the indentation 41. Adiameter, or, more generally, an area of cross section, of theindentation is larger than a diameter/area of cross section of thecylindrical portion of the fastener. In the region of the indentation(if present) or generally at the spot where during compression of thefastener the fastener is in contact with the counter element, thecounter element may comprise an optional coating of a non-stickingmaterial so as to ease releasing the removal of the counter element fromthe fastener after the process.

In the depicted configuration, the instrument further comprises anoptional spring 16. In accordance with a first option, the spring may inthe configuration of FIG. 1 be pre-tensioned to pull the first andsecond instrument components towards each other so as to compress thefastener between the sonotrode 6 and the foot 13. This provides apre-defined compression force during the compression step. In accordancewith a second option, the spring may be such as to be compressed whenthe sonotrode and the counter element are pressed against each other soas to provide a release mechanism after the process.

FIG. 2 shows the assembly at the end of the step of simultaneouslypressing the sonotrode and the counter element towards each other whilecoupling vibrations into the sonotrode and thus the fastener. The distalend of the fastener is deformed to yield a distal head 25 the shape ofwhich is defined by the indentation. Also the proximal head 22 and/orthe cylindrical portion may be deformed. The result of the process is arivet that permanently clamps the two tissue parts on each other.

In the depicted configuration, the stiffness of the tissue parts isassumed to be sufficient so that the distal end of the fastener does notpress the tissue against the bottom of the indentation. Rather, thesecond tissue parts lies against a flat portion 16 of the foot 13proximal surface, which flat portion 16 surrounds the indentation 14.The fastener 21 pierces the tissue letting a space for the distal headto form underneath the second tissue part 2. In situations where thestiffness is not sufficient, the common opening may be pre-formed tohave a diameter corresponding to the cylindrical portion of the fasteneror slightly larger than the latter. In these embodiments, the tissueparts are advantageously provisionally fixed relative to each otherafter pre-forming the common opening, for example by surgical clamps. Itis also possible to provide the fastener with a retractable punchingsheath that first punches the common opening and is then retracted whilethe fastener body having the cylindrical portion remains in the opening;in these embodiments the fastener advantageously does not have apre-formed proximal head, but the proximal head—like in otherembodiments—is formed only during the process.

Also the sonotrode may comprise an indentation so as to define the shapeof the proximal head.

A variant of the set-up shown in FIGS. 1 and 2 is depicted in FIGS. 3aand 3b . FIG. 3a shows the variant while the fastener 21 is introduced,and FIG. 3b shows it at the end of the step of causing material to beliquefied by the effect of mechanical energy.

As a first difference to the assembly in FIGS. 1 and 2, that the secondinstrument component 11 of the assembly on FIGS. 3a and 3b is notnecessarily guided by a guiding element mechanically connected to thefirst instrument component but is held independently. For example, thesurgeon performing the operation may hold the vibration generatinginstrument comprising the first instrument component in one hand and thesecond instrument component in the other hand.

Further, the second instrument component 11 comprises a magazine 50 offastener head forming elements 51 that may be during the step ofcoupling mechanical vibrations into the fastener welded to the fastenerso that the fastener after the step comprised the material of the headforming element in addition to the material it initially consisted of.

At least one distal head forming element carried by the secondinstrument component, for example in a magazine of head formingelements, may also be used in any embodiment. For example, it may beused together with a first instrument component of the kind shown inFIGS. 1 and 2, for example with the first instrument componentcomprising a guiding element for the second instrument component and/ora spring mechanism for automatically excerpting the necessary force. Thehead forming element magazine may comprise a spring or the like capableof automatically feeding a head forming element into the workingposition (where it forms part of the contact surface) when the last headforming element was used.

The embodiment of FIGS. 4a-4c shows a variant where the fastener 21having a distal head 22′ is initially carried by the second instrumentcomponent and is introduced from the distal side. To this end, thefastener may optionally be equipped to pierce the tissue parts (ortissue and implant portion) that it fastens together. A piercingfastener may also be used in embodiments where it is introduced from theproximal side.

In embodiments with a piercing fastener, the common opening need not bepre-made by a separate instrument or similar but may be made byintroducing the fastener. As yet another alternative (that may becombined with any embodiment), an initial opening of at least one of thetissue parts may be smaller than the final common opening in at leastone dimension and may be expanded by introducing the fastener.

FIG. 4a depicts the initial step of introducing the fastener from thedistal side by the second instrument component 11. After this has beenaccomplished, the vibration generating instrument comprising the housing4 and the second instrument component 6 (the sonotrode) is used toliquefy the proximal end portion of the fastener and to form a proximalhead 25′, as shown in FIGS. 4b and 4c . To this end, the sonotrode 6comprises a distal head shaping portion being a shallow indentation 54similar to the shallow indentation 14 of the foot in the previousembodiments.

While in the embodiments of FIGS. 1-3 b the vibration energy is at leastpartially transmitted through the fastener and is primarily absorbedunder the generation of heat at the distal end in contact with the foot,in the embodiment of FIGS. 4a-4c , absorption of vibration energyprimarily takes place at the location of contact between the sonotrodeand the fastener.

Generally, at the site of liquefaction (at the distal end portion of thefastener in FIGS. 1-3 b and at the proximal end portion in FIGS. 4a-4c), a head shaping portion may be provided in the second instrumentcomponent or the first instrument component, respectively. As describedhereinbefore, the head shaping portion may comprise a surface structurethat has the form of an indentation, for example a shallow indentation.The contour of the indentation then may correspond to the contour of thehead that is to be formed. Further, the head shaping portion maycomprise material directing and/or energy directing structures. Energydirecting structures, as are known from the technology of ultrasonicwelding, may help to determine the spot(s) at which liquefaction sets inwhen the vibration energy is coupled into the sonotrode. A materialdirecting structure may help to distribute the molten material in adesired manner. FIG. 5a shows, in section, the end portion of a foot 13of a second instrument component. In a middle of the indentation 14, aridge 15 is formed that may serve both, as energy directing structureand as material directing structure for material from a fastener that ispressed against the foot (from above in the orientation shown in thefigure) while mechanical vibrations are coupled into it. An analogousstructure may be present in a sonotrode if a configuration as shown inFIGS. 4a-4c is chosen, where the fastener is introduced from the distalside.

FIG. 5b yet shows a top view of an head shaping portion where theindentation 14 has an outer contour that is not circular but comprises acentral section 17 the diameter of which may be similar to the diameterof the fastener or only slightly enhanced and lobes 16 extending inopposing directions. Almost arbitrary other shapes (circular,elliptical, one or more than two lobes, symmetrical or asymmetricaletc.) adapted to the requirements and geometrical conditions arepossible; also the fastener's shaft need not be circular in crosssection, because in contrast to prior art methods neither the insertionof the fastener nor any other step during the process necessarilyrequires a rotational movement of the fastener.

Whereas the head shaping portion in FIG. 5b is shown to be a structureof the foot 13, in embodiments that comprise insertion of the fastenerfrom the distal side, such a structure may be present also at thesonotrode.

The instrument 3 shown in FIG. 6 is particularly suited for situationswhere the operation site has to be accessed from a side. The firstinstrument component 6 has a device 61 that deflects mechanicaloscillation from a transversal oscillation along an input axis to atransversal mechanical oscillation along a second axis. Such a device isdescribed in WO 2007/101 362/US 2010/0 179 654 incorporated herein byreference in its entirety. Especially, the embodiment of the oscillationdeflection device 61 shown in the figure is based on the devicedescribed referring to FIG. 3a and the corresponding description in WO2007/101 362, however, other embodiments may be used also.

As a further feature, the second instrument component 11 is pivotinglymounted to the housing 4, and the foot 13 may be pressed against thefirst instrument component 6 by pivoting a lever 71. In the depictedembodiment, the fastener 21 is attached to the second instrumentcomponent and is to be inserted from the distal side, however, it wouldalso be possible to provide the fastener at the side of the oscillationdeflection device 61.

FIG. 7 illustrates the use of a flexibly bendable planar structure ofartificial material (or possibly of autograft or allograft tissue), suchas a mesh to reinforce the tissue parts and/or their connection. In theconfiguration shown in FIG. 7, two flexible planar structures beingmeshes 71 are used, each placed in contact with one of the tissue parts1, 2. The meshes are placed on the outer sides, so that the tissue partsare in direct contact with each other. The reinforcement provided by themeshes (or other flexible planar structures) may especially be valuablein case multiple fasteners are used, as illustrated by the two fasteners21 in FIG. 7. The reinforcement can absorb in-plane forces thatotherwise would act on the tissue parts at the common opening.

Instead of the depicted configuration with two tissue parts and twoouter flexible planar structures, other configurations are possible asdescribed hereinbelow.

Providing only one flexible planar structure, either in contact with oneof the tissue parts or between the tissue parts. In the latter case theflexible planar structure may optionally be of a kind promoting thegrowth of tissue for the tissue parts to adhere to each other.

Providing one or more flexible planar structure(s) instead of one of thetissue parts. The method is then a method of fixing a tissue part to aan implant part, namely to the flexible planar structure that forexample reinforces the tissue part or has another function, such ascovering and retaining (other) soft tissue, for example in the event ofa hernia.

In each of these configurations, using only one fastener or more thantwo fasteners.

FIGS. 8a and 8b show the use of a guided needle to connect afilament-like element to the tissue part or tissue parts. The foot 13 ofa second instrument component comprises a channel through which abendable needle 81 is guided to pierce the tissue part or tissue parts1, 2. The needle may for example be of a shape memory material thatautomatically goes into a stretched configuration after it exits thechannel 82 through which it is guided. The needle may for example be ofnitinol. The needle is guided by the channel through a part of the footand then pierces the tissue part or tissue parts from the distal sideand exits on the proximal side where it is accessible to the surgeon.

The filament-like element may for example be attached to the needle tipor to an attachment spot close to the needle tip so that the needlepulls it through the tissue part/tissue parts when piercing.Alternatively, the needle may be cannulated, and the filament-likeelement may be pushed through the cannulation. In these cases, theneedle is completely retracted after the filament-like element has beenguided through the tissue As yet another alternative, the needle itselfor a part of the needle (for example except a nitinol end portion thatcomprises the sharp tip) may constitute the filament-like element, bybeing formed into the desired shape after the piercing step.

FIG. 8b shows how the filament-like element's 83 end portion is formedinto a loop through which the shaft of the fastener 21 goes. Thefilament-like element is then attached to the proximal side of thetissue part(s), guided through the piercing hole to the distal side andalong the side of the tissue part(s) back to the proximal side. Thesurgeon may use the filament-like element to thread the tissue part(s)'end portion to some other element or to otherwise excerpt a force on it.

The filament-like element may be a surgical thread or other filament.The loop or other structure attaching the filament-like element to thefastener so that it can be subject to a tensile load may be made priorto the insertion of the fastener 21 or possibly also thereafter.Additionally or as an alternative, the filament-like element may bewelded to the fastener during or after insertion of the latter.

FIG. 9 schematically depicts the principle of a foot being provided witha dispenser 90 for automatically dispensing, for example by means of aspring mechanism 91, fasteners, especially for a configuration asdescribed referring to FIGS. 4a -4 c.

Whereas the fasteners 21 in the hereinbefore described embodimentscomprise a single fastener body or shaft 24 that is configured to reachthrough a single common opening of the tissue parts/tissue and implantparts, the invention is also suited for fasteners with a plurality ofshafts 24 that are connected by a bridging portion 26 and that are thusconfigured to reach through a corresponding number of common openings.The bridging portions after the process rest against the tissue (orimplant part) and replace or enhance the function of the optionalpre-formed (proximal or distal) head 22. FIG. 10 shows an embodimentwith two shafts, and FIG. 11 depicts and embodiment with three shafts.Other configurations are possible, for example with more than two shaftsin a row, for example, three, four, five, to the point of a comb-likearrangement, or with other geometries that do not form a row like inFIG. 11. Also, any bridge portion shape can be chosen, in accordancewith the needs of the surgeon.

The instrument component in contact with which the head is formed(generally, the instrument component with the head shaping portionand/or with the head forming element(s) is configured correspondingly.For embodiments where the fastener 21 is inserted from the proximalside, this concerns the foot 13 of the second instrument component.FIGS. 12-15 illustrate this for the example fastener of FIG. 10. In FIG.12, the foot comprises two head shaping indentations for shaping a headat the distal end of each of the two shaft portions so that the fastenerafter being implanted comprises two distal heads. An alternative isdepicted in FIG. 13. A common head shaping indentation forms a distalhead that also comprises a bridge portion, like the pre-shaped proximalportion of the fastener. The same principles apply in case the distalhead is provided using a head forming element. As a first option, twoindividual head forming elements 51 are provided (FIG. 14), whereas asecond option suggests a common head forming element 51 that has a brideportion.

Whereas FIGS. 12-15 relate to configurations where the fastener isinserted from the proximal side and comprises two shafts, sameconsiderations apply for fasteners inserted from the distal side and/orwith more than two shafts.

What is claimed is:
 1. A method of fixing a first and a second part toeach other, the method comprising the steps of providing a fastenercomprising a thermoplastic material, providing a fastening instrument,the fastening instrument comprising a first instrument component with afirst contact surface and a second instrument component with a secondcontact surface, the first instrument component and the secondinstrument component being displaceable with respect to each other,positioning the fastener and the fastening instrument so that thefastener reaches through a common opening of the first and second parts,which common opening is constituted by a first through opening of thefirst part and a second through opening of the second part, the firstand second through openings aligned with each other, and so that thefirst contact surface is in contact with a proximal end face of thefastener and the second contact surface is in contact with a distal endface of the fastener, submitting the first and second instrumentcomponents to a relative force so that the fastener is pressed betweenthe first and second contact surfaces, and simultaneously couplingmechanical vibrations into at least one of the first and secondinstrument components with a vibration power and during a vibration timesufficient to at least partially soften and/or melt an end portion ofthe fastener under the common impact of the relative force and thevibrations, and using the softening and/or melting of the end portion toprovide the end portion with a head with a diameter greater than adiameter of at least one of the through openings, and letting thesoftened and/or melted end portion re-solidify; wherein the methodcomprises the further step of providing a filament-like element andcausing the filament-like element to form a loop portion, wherein afterthe step of letting the softened and/or melted end portion re-solidifythe loop portion encircles a portion of the fastener, wherein either thefirst part is a first tissue part and the second part is a second tissuepart or wherein the first part is a tissue part and the second part isan implant part.
 2. The method according to claim 1, wherein in the stepof using the softening and/or melting of the end portion to provide theend portion with a head, the end portion is caused to deform, under thecommon impact of the relative force and the vibrations, to yield thehead.
 3. The method according to claim 2, wherein the end portion itselfis deformed into the head.
 4. The method according to claim 1, whereinprior to the step of submitting the first and second instrumentcomponents to a relative force and coupling mechanical vibrations intoat least one of the instrument components, a head forming element isprovided, and wherein during said step of submitting the first andsecond instrument components to a relative force and coupling mechanicalvibrations into at least one of the instrument components, the headforming element is in contact with the end portion and is, by thesoftening and/or melting, welded to the end portion so that the head isformed.
 5. The method according to claim 1, wherein the fastener ispositioned by being inserted from a proximal side, wherein the endportion that is provided with a head is a distal portion, and whereinthe head is a distal head.
 6. The method according to claim 1, whereinprior to the step of positioning the fastener, the fastener istemporarily mounted to the second instrument component, and wherein thefastener is positioned by being inserted from a distal side.
 7. Themethod according to claim 1, comprising the further step of placing,prior to the step of positioning the fastener, a flexible planarstructure of an artificial material in contact with at least one of thefirst part or the second part, wherein in the step of positioning thefastener, the fastener is positioned to reach through an opening of theflexible planar structure.
 8. The method according to claim 1, whereinafter the step of letting the softened and/or melted end portionre-solidify the loop portion is covered by the head.